JP2001021797A - Focus detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify constitution for a focus detecting optical system by using in common a diaphragm opening of a diaphragm mask and a re-image-focusing lens part of a re-image-focusing optical system, in a focus detector provided with a large number of focus detecting regions. SOLUTION: This detector has a focus detecting region having a cross-shaped visual-field opening 204 in a position different from that on a line connecting centers of the first and second focus detecting regions corresponding to the visual-field openings 201, 202, diaphragm openings 401, 404 and re-image-focusing lens parts 501, 504 corresponding to the first focus detecting region are used for an image transmitted through one rectangular visual-field opening of the cross-shaped openings 204, and diaphragm openings 406, 408 and re-image- focusing lens parts 506, 508 corresponding to the second focus detecting region are used for an image transmitted through the other rectangular visual-field opening. Constitutional elements for a focus detecting optical system are simplified remarkably thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detecting device used for a single-lens reflex camera or the like.

[0002]

2. Description of the Related Art In general, as a focus detection device having a plurality of focus detection areas, a focus difference detection system as shown in FIGS. FIG. 3 is a perspective view showing a schematic configuration of a conventional focus detection device, and FIG. 4 is a schematic optical path diagram of the focus detection device 90 shown in FIG. 3 as viewed from the y-axis direction in the drawing. The light beam from the object field forms an image near the field mask 20 via a not-shown photographing lens. Of the luminous flux from the object scene, the luminous flux passing through the rectangular field opening 22 extending in the x-axis direction passes through the lens portion 32 of the condenser lens 30 and passes through the photographing lens, as shown by principal rays r2a and r2b shown in FIG. Are divided via the aperture openings 43 and 44 of the aperture mask 40 and the re-imaging lens units 53 and 54 of the re-imaging optical system 50 which are arranged at positions substantially conjugate with the exit pupil of the CCD chip 60, respectively. An image is formed on columns 63 and 64.

Then, by subjecting a pair of subject images formed on the light receiving element arrays 63 and 64 to photoelectric conversion, it is possible to detect a focus adjustment state of the photographing lens. That is,
When the focus adjustment state of the taking lens forms a sharp image on the film equivalent surface, that is, at the time of so-called focusing, the light receiving element arrays 63 and 64 are provided.
Each position of the upper pair of subject images forms an image at a predetermined interval between the front focus state and the rear focus state. Further, when the focus adjustment state of the photographing lens is a so-called front focus state in which a sharp image is formed ahead of the film equivalent surface, the respective positions of the pair of subject images on the light receiving element arrays 63 and 64 are:
An image is formed at a first interval shorter than a predetermined interval. Conversely, when the focus adjustment state of the photographing lens forms a sharp image behind the film equivalent plane, that is, in a so-called rear focus state, the respective positions of the pair of subject images on the light receiving element arrays 63 and 64 are:
An image is formed at a second interval longer than a predetermined interval. Therefore, the pair of subject images is photoelectrically converted by the light receiving element arrays 63 and 64 into electric signals.
As in the displacement amount detection device disclosed in Japanese Patent Laid-Open No. 3 (1999) -2003, by performing a correlation operation or the like from these electric signals, the relative position displacement amount between a pair of subject images is obtained. The focus adjustment state of the taking lens is detected.

[0004] Of the luminous flux from the object field, the luminous flux passing through the rectangular visual field opening 21 extending in the y-axis direction of the visual field mask 20 is reflected by the condenser lens 30 like the principal rays r2c and r2d shown in FIG. The aperture mask 4 is passed through the lens unit 31.
0 through aperture stops 41 and 42 and the re-imaging lens units 51 and 52 of the re-imaging optical system 50, respectively.
An image is formed on the light receiving element arrays 61 and 62 of the D chip 60. Similarly, the luminous flux passing through the field opening 23 is changed to the principal ray r shown in FIG.
2e and r2f, the aperture openings 45 and 46 of the aperture mask 40 via the lens unit 33 of the condenser lens 30.
Further, the light is divided via the re-imaging lens portions 55 and 56 of the re-imaging optical system 50, and forms an image on the light receiving element arrays 65 and 66 of the CCD chip 66, respectively. Then, the light receiving element array 61,
A pair of subject images on the light receiving element rows 65 and 66 form a pair of subject images on the field opening 23.
The focus state of the taking lens in the focus detection area outside the optical axis corresponding to is detected.

In this way, focus detection in a plurality of focus detection areas has been enabled. Also, JP-A-2-50115
Japanese Patent Application Publication No. JP-A-2005-115122 discloses a focus detection device in which a focus detection area is arranged on a diagonal line of a shooting screen.

[0006]

As described above, when a plurality of focus detection areas are provided in a photographing screen, an aperture for forming a pair of subject images on a light receiving element array and a re-imaging lens section are provided. However, one pair is required for each focus detection area. Also, a rectangular field opening 2 extending in the x-axis direction
2, focus detection cannot be performed on a subject having a luminance change in the x-axis direction. In a focus detection area formed by rectangular visual field openings 21 and 23 extending in the y-axis direction, the y-axis Focus detection could not be performed on a subject having a luminance change in the direction.

In Japanese Patent Laid-Open Publication No. Hei 2-50115, focus detection areas are arranged on a diagonal line of a photographing screen in order to increase the number of focus detection areas so that focus detection can be performed at more positions. However, a pair of aperture openings and a pair of re-imaging lens units are required for each focus detection area. Further, in the focus detection area corresponding to the cross-shaped field opening, two pairs of aperture masks and a re-imaging lens unit are required, which causes a problem that the focus detection apparatus becomes large and the focus detection optical system itself becomes complicated. is there.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to simplify the structure of the focus detection optical system despite having many focus detection areas, and to be weak in all focus detection areas. An object of the present invention is to provide a focus detection device capable of greatly reducing the number of subjects to be set.

[0009]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: Multiple field apertures (201, 202) corresponding to
A field mask (200) comprising:
0), a plurality of lens units (301, 30) for condensing light beams transmitted through the plurality of field openings (201, 202), respectively.
2) A condenser lens (300) having a plurality of light beams transmitted through a plurality of field apertures (201, 202) and a plurality of light beams transmitted through different regions of the exit pupil of the photographing lens (100). Aperture aperture (401, 4
02,403,404,405,406,407,40
8) and a plurality of re-imaging lens units (501, 502, 50) for forming images of the plurality of field openings (201, 202) on the light receiving means (600).
3, 504, 505, 506, 507, 508) in a focus detection device having a re-imaging optical system (500), at a position different from a line connecting the centers of the first and second focus detection areas. A focus detection area having a cross-shaped field opening (204);
The image transmitted through one of the rectangular viewing apertures in 4) is the first image.
Aperture openings (401, 404) corresponding to the focus detection areas of
The image transmitted through the other rectangular field opening is connected to the aperture openings (406, 408) corresponding to the second focus detection area and the re-imaging lens unit (501, 504).
6,508) is used.

According to a second aspect of the present invention, the focus detection area includes:
All have a cross-shaped field opening.

[0011]

FIG. 1 is a perspective view showing a schematic configuration of a focus detection device according to the present invention, and FIG. 2 is a front view when a CCD chip is viewed from a subject side. The light beam from the object field forms an image near the field mask 200 via the taking lens 100. The visual field mask 200 has a plurality of visual field openings 201, 202, 203, 204, 205, 206, 2
07, the field opening 202 corresponds to the focus detection area at the center of the photographing screen, and the field openings 201 and 203 correspond to the photographing lens 1.
Corresponding to the focus detection area at a position deviated from the optical axis L of 00,
The field openings 204, 205, 206, and 207 correspond to the field opening 2
Of the focus detection areas corresponding to 01, 202, and 203, the focus detection areas correspond to focus detection areas at positions different from a line connecting the centers of at least two focus detection areas. The condenser lens 300 includes lens units 301, 302, 303, 30
4,305,306,307.

The image transmitted through the visual field openings 201, 202, and 203 will be described in detail. Of the light flux from the object field, the light flux passing through the rectangular opening extending in the x-axis direction of the visual field opening 202 is a condenser lens. 300 lens unit 30
2, the aperture openings 405, 40 of the aperture mask 400 arranged at a position substantially conjugate with the exit pupil of the taking lens 100
6 and the re-imaging lens unit 505 of the re-imaging optical system 500
506, and each of the CCD chips 600
Are formed on the light-receiving element arrays 605 and 606 of FIG. View opening 2
A light beam passing through a rectangular opening extending in the y-axis direction of No. 02 passes through the lens portion 302 of the condenser lens 300, and the aperture openings 407, 407, of the aperture mask 400 arranged at a position substantially conjugate with the exit pupil of the photographing lens 100. 408 and the re-imaging lens units 507 and 508 of the re-imaging optical system 500, and are divided into light-receiving element rows 6 of the CCD chip 600, respectively.
07,608.

[0013] Of the luminous flux from the object field, the luminous flux passing through a rectangular opening extending in the x-axis direction of the field opening 201 is:
The aperture openings 401 and 402 of the aperture mask 400 and the re-imaging lens portions 501 and 502 of the re-imaging optical system 500 are arranged at positions substantially conjugate with the exit pupil of the photographing lens 100 via the lens portion 301 of the condenser lens 300. And form an image on the light receiving element arrays 601 and 602 of the CCD chip 600, respectively. A light beam passing through a rectangular opening extending in the y-axis direction of the field opening 201 passes through the lens unit 301 of the condenser lens 300 and passes through the photographing lens 100.
Aperture mask 40 arranged at a position substantially conjugate with the exit pupil of
0 aperture apertures 403 and 404 and re-imaging optical system 500
Are divided via the re-imaging lens units 503 and 504, and the light receiving element rows 603 and 604 of the CCD chip 600 are respectively divided.
Image on top.

Further, of the luminous flux from the object field, the luminous flux passing through the rectangular opening extending in the x-axis direction of the visual field opening 203 opposite to the visual field opening 201 is converted into a condenser lens 30.
0, through the aperture openings 409, 410 of the aperture mask 400 and the re-imaging lens units 509, 510 of the re-imaging optical system 500, which are arranged at a position almost conjugate with the exit pupil of the taking lens 100. Divided into C
An image is formed on the light receiving element rows 609 and 610 of the CD chip 600. The luminous flux passing through the rectangular opening of the field opening 201 extending in the y-axis direction passes through the lens unit 3 of the condenser lens 300.
03, the aperture openings 411, 4 of the aperture mask 400 arranged at a position substantially conjugate with the exit pupil of the photographing lens 100
12 and re-imaging lens unit 51 of re-imaging optical system 500
1, 512, and each of the CCD chips 6
An image is formed on the light receiving element arrays 611 and 612 of 00.

As described above, the field openings 201, 202, 2
The focus detection area corresponding to 03 has two unique pairs of aperture openings 40 (because they are cross-shaped field apertures).
1,402,403,404,405,406,40
7, 408, 409, 410, 411, 412 and re-imaging lens units 501, 502, 503, 504, 505, 5
06,507,508,509,510,511,51
2 is used.

Viewing apertures 204, 205, 206, 207
The image transmitted through the lens will be described in detail. Among the light fluxes from the object field, the light flux passing through the rectangular opening extending in the circumferential direction with respect to the optical axis L of the taking lens 100 in the field opening 204 is a condenser lens. The apertures 406 and 408, which are apertures corresponding to the field apertures 202 of the aperture mask 400 disposed at a position substantially conjugate with the exit pupil of the photographing lens 100, via the lens unit 304 of the imaging lens 100, and the re-imaging optical system 500. It is divided via re-imaging lens units 506 and 508 which are re-imaging lens units corresponding to the field opening 202,
The light receiving element rows 623 and 62 of the CCD chip 600, respectively.
4. The light beam passing through the rectangular opening of the field opening 204 extending in the radial direction with respect to the optical axis L of the photographing lens 100 passes through the lens portion 304 of the condenser lens 300 and is substantially conjugate with the exit pupil of the photographing lens 100. The aperture opening 40 which is an aperture opening corresponding to the field opening 201 different from the field opening 202 of the arranged aperture mask 400.
1,402 and the field aperture 202 of the re-imaging optical system 500
Are divided via re-imaging lens portions 501 and 502 which are re-imaging lens portions corresponding to the field opening 201 different from
Each of the light receiving element rows 615 and 61 of the CCD chip 600
6 is formed.

Among the light beams from the object scene, the light beams passing through the rectangular opening extending in the circumferential direction with respect to the optical axis L of the taking lens 100 in the field opening 205 are passed through the lens portion 305 of the condenser lens 300. , An aperture aperture 40 which is an aperture aperture corresponding to the field aperture 202 of the aperture mask 400 arranged at a position substantially conjugate to the exit pupil of the taking lens 100
6,407 and field aperture 202 of re-imaging optics 500
Re-imaging lens unit 50 which is a re-imaging lens unit corresponding to
6,507, and each of the CCD chips 6
An image is formed on the light receiving element arrays 621 and 622 of 00. The light beam passing through a rectangular opening of the field opening 205 extending in the radial direction with respect to the optical axis L of the taking lens 100 passes through the lens unit 305 of the condenser lens 300 and is substantially conjugate with the exit pupil of the taking lens 100. The aperture openings 401 and 403, which are aperture stops corresponding to the field aperture 201 different from the field aperture 202 of the arranged aperture mask 400, and the refocusing corresponding to the field aperture 201 different from the field aperture 202 of the re-imaging optical system 500. Re-imaging lens unit 501, which is an image lens unit
503, each of which is divided into CCD chips 600
Are formed on the light receiving element rows 613 and 614 of the image forming apparatus.

Further, of the luminous flux from the object field, the luminous flux passing through a rectangular opening extending in the circumferential direction with respect to the optical axis L of the photographing lens 100 in the field opening 206 is passed through the lens unit 306 of the condenser lens 300. Aperture mask 400 arranged at a position substantially conjugate with the exit pupil of the taking lens 100
Aperture 4 which is a diaphragm aperture corresponding to the field aperture 202 of FIG.
05, 408 and the field aperture 20 of the re-imaging optical system 500
Re-imaging lens unit 50 which is a re-imaging lens unit corresponding to 2
5,508, and each of the CCD chips 6
An image is formed on the light receiving element arrays 619 and 620 of 00. The light beam passing through the rectangular opening of the field opening 206 extending in the radial direction with respect to the optical axis L of the photographing lens 100 passes through the lens portion 306 of the condenser lens 300 and is substantially conjugate with the exit pupil of the photographing lens 100. The aperture openings 410 and 412, which are aperture openings corresponding to the field aperture 203 different from the field aperture 202 of the arranged aperture mask 400, and the refocusing corresponding to the field aperture 203 different from the field aperture 202 of the re-imaging optical system 500. A re-imaging lens unit 510 which is an image lens unit,
Through the CCD chip 600
Are formed on the light-receiving element arrays 627 and 628 of FIG.

Further, of the luminous flux from the object field, the luminous flux passing through a rectangular opening extending in the circumferential direction with respect to the optical axis L of the taking lens 100 at the field opening 207 is a lens of the condenser lens 300. 307, the photographing lens 10
A stop mask 4 arranged at a position almost conjugate with the exit pupil of 0
The aperture is divided via aperture stops 405 and 407, which are aperture apertures corresponding to the field aperture 202 of 00, and re-imaging lens sections 505, 507 which are aperture lenses corresponding to the field aperture 202 of the re-imaging optical system 500. Then, an image is formed on the light receiving element rows 617 and 618 of the CCD chip 600, respectively. The light flux passing through the rectangular opening of the field opening 207 extending in the radial direction with respect to the optical axis L of the photographing lens 100 passes through the lens unit 307 of the condenser lens 300 and passes through the photographing lens 100.
Aperture mask 40 arranged at a position substantially conjugate with the exit pupil of
The aperture apertures 410 and 411 which are aperture apertures corresponding to the field aperture 203 different from the field aperture 202 of 0, and the field aperture 20 different from the field aperture 202 of the re-imaging optical system 500.
Re-imaging lens unit 51 which is a re-imaging lens unit corresponding to 3
0, 511, and each of the CCD chips 6
An image is formed on the light receiving element arrays 625 and 626 of 00.

Thus, the field openings 204, 205, 2
06,207 pass through the field openings 201,20.
An aperture and a re-imaging lens unit corresponding to a focus detection area corresponding to 2,203 are used. In FIG. 2, the relationship between the field aperture and the field aperture image will be described. The field opening 201 is set to the field opening images 701, 702, 703, and 704, and the field opening 202 is set to the field opening images 705, 706, 707, and 708.
The field aperture 203 has field aperture images 709, 710, 71.
1, 712, the field aperture 204 has field aperture images 715, 7
16, 723, 724, the field opening 205 is in the field opening images 613, 614, 721, 722, the field opening 206 is in the field opening images 719, 720, 727, 728, the field opening 207 is the field opening images 717, 718, 725,726
Respectively.

In the above configuration, for example, the aperture mask 40
The aperture stop 405 of 0 and the lens unit 505 of the re-imaging lens 500 are connected to the field openings 202 and 20 of the field mask 200.
6 and 207. That is, the same aperture opening and re-imaging lens unit are used even for light beams from different field openings. Therefore, the configuration of the focus detection optical system can be greatly simplified.

The aperture and re-imaging of a focus detection area located at a position different from a line connecting the centers of at least two focus detection areas among the focus detection areas corresponding to the field openings 201, 202, and 203. The lens portion includes a rectangular shape extending in the circumferential direction with respect to the optical axis L of the photographing lens 100 and a rectangular shape extending in the radial direction.
Since a stop aperture and a re-imaging lens unit corresponding to different field apertures among the three are used, a cross-shaped focus detection area can be configured in all the focus detection areas, greatly reducing the number of subjects that are not good at focus detection. Can be reduced to

[0023]

As described above, according to the first aspect, the first and the second using the unique aperture aperture and the re-imaging lens unit, respectively.
Has a focus detection area having a cross-shaped field opening at a position different from the line connecting the centers of the focus detection areas, and an image transmitted through one rectangular field opening of the cross-shaped field aperture is the first image. The aperture opening and the re-imaging lens unit corresponding to the focus detection area are used, and the image transmitted through the other rectangular field opening uses the aperture opening and the re-imaging lens unit corresponding to the second focus detection area. Therefore, the components of the focus detection optical system can be greatly simplified.

According to a second aspect of the present invention, in the focus detection device of the first aspect, all the focus detection areas have a cross-shaped field opening, so that the number of components of the focus detection optical system is not increased. In addition, it is possible to significantly reduce the number of subjects who are not good at focus detection.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a focus detection device of the present invention.

FIG. 2 is a front view showing a CCD chip in the focus detection device of the present invention.

FIG. 3 is a perspective view illustrating a schematic configuration of a conventional focus detection device.

FIG. 4 is a schematic optical path diagram of the focus detection device shown in FIG.

[Explanation of symbols]

20, 200 field mask 21 to 23, 201 to 207 field aperture 30, 300 condenser lens 31 to 33, 301 to 307 lens part of condenser lens 40, 400 aperture mask 41 to 46, 401 to 412 aperture mask aperture aperture 50, 500 Re-imaging optical system 51-56, 501-512 Re-imaging lens unit of re-imaging optical system 60,600 CCD chip 61-66,601-628 Light receiving element array 701-728 Field opening image 90,900 Focus detection Apparatus 100 shooting lens

Claims (2)

[Claims] 1. A field mask which is arranged near a predetermined imaging plane of a taking lens and has a plurality of field openings corresponding to first and second focus detection areas; and the plurality of field apertures of the field mask. A condenser lens having a plurality of lens units for condensing light beams transmitted through the light source; and a light beam transmitted through each of the plurality of field apertures is split into a pair of light beams transmitted through different areas of the exit pupil of the photographing lens. A focus detection device comprising: an aperture mask having a plurality of aperture apertures; and a re-imaging optical system having a plurality of re-imaging lens units for imaging the images of the plurality of field apertures on a light receiving unit. A focus detection area having a cross-shaped field opening at a position different from a line connecting the center of the second focus detection area and the center of the second focus detection area; The image transmitted through the field aperture is the aperture opening and the re-imaging lens unit corresponding to the first focus detection area, and the image transmitted through the other rectangular field opening is the aperture aperture corresponding to the second focus detection area. And a re-imaging lens unit. 2. The focus detection device according to claim 1, wherein the focus detection areas all have a cross-shaped field opening.